Process of obtaining boric acid from mixtures containing borates



R. P. CALVERT AND 0. L. THOMAS.

PROCESS OF OBTAINING BORIC ACID FROM MIXTURES CONTAINING BOBATES.

APPLICATION FILED NOV. 5. I9I7.

1,308,577. Patented July 1, I919.

oNiTEn sTATns PATENT orator...

ROBERT P. CALVERT AND OTHO L. THOMAS, 0F WILMINGTON. DELAWARE. ASSIGNORS TO E. I. DU PONT DE NEMOURS AND COMPANY, OF WILMINGTON, DELAWARE, A COR- PORATION OF DELAWARE.

PROCESS OF OBTAINING BORIC ACID FROM MIXTURES CONTAINING BORATES.

Specification of Letters Patent.

Patented July 1, 1915).

Application filed November 5. 1917. Serial No. 200.439.

To all, who) it '77Ill 't/ concern:

scription thereof.

Our invention relates to a process of obtaining boric acid from mixtures containing borates. and relates particularly to a process in which boric acid is combined with an alcohol and the resulting alkyl borate is volatilized.

The object of our invention is to provide a. process for obtaining boric acid from mixtures containing borates, and particularly mixtures of soluble salts containing the same. so that said salts will be freed from the borates and the bot-ates may be used in any desired manner for the production of compounds of boron.

Further objects of our invention willappear from the detailed (lt'St'llllllOli thereof contained hereinafter.

\Vhile our invention is capable of being carried out in many different ways, we shall describe herein only certain ways of carrying out the same. and while it is capable of being used in connection with many different types of apparatus, we shall describe only one type of apparatus for use in connection therewith and in the accompanying drawings. in which The figureis a diagrammatic representation of an apparatus which may be used in connection with our invention.

In the drawings. we have shown a jacketed still 1. having a steam inlet 1 and a steam outlet 1 for heating the still. The still is further provided with a valved filling pipe 1 for methyl alcohol. a gage and a vapor outlet pipe 2 which has glass 1 an inletpipe 2" for air or steam. said pipe 2 being arranged to deliver the vapor therefrom into a rotary drum 3. having hollow trunnions i' and 4. carried in suitable su The drum 3 is adapted to orts 5 and 5. e rotated by means of peripheral gears (3. meshing with a gear 7 on av shaft h. passing through the supports 3. and adapted to he driven from an) suitable source of power. The drum 3 has a heating jacltct 9. adapted to be supplied with steam through the. hollow trunnion which connects with a steam supply pipe 10. while the condensed steam is carried oil through a pipe 10. manhole 10 in the drum 3 permits the entry and exit of the solid materials for the same. The vapors from the drum 3 pass out through a pipe 11. which is connected to a condenser 12. having an outlet pipe 13. leading to a fractionating still 14. The still 14 has a water inlet pipe 13. connected to the pipe 13. a draw--otl' pipe 13*. and a vapor outlet pipe 15 leading to a primary condenser 15 having a trap return pipe 15* leading to the vapor outlet pipe 15. and thence to a condenser ill. from which the condensed materials are drawn oil through an out let pipe 17.

For example. our invention may he carried out as follows: quantity of a material. which may be a mixture of a number of compounds. for example 700; of potassium chlorid. 121-; of sodium chlorid. 1'; of so dium carbonate. 2" of sodium sulfate. 11%. of borax and -lof water. is mixed with a quantity of hydrochloric acid. or some other acid. such for example as sulfuric acid. in the drum 3. For this purpose. 100 parts of said material may be mixed with 5.6 parts of hydrochloric acid having a strength of 23 Be. The mixture is slightly warmed, while, the drum 3 is rotated. in the presence of an alcohol. for example methyl alcohol, which has been distilled over by introducing 40 parts of methyl alcohol into the still 1 and applying heat thereto. This converts the borates into boric acid. and the methyl alcohol combines with the boric acid to give methyl horate. which is thereafter volatilined in the drum 3 and distilled off, together with the remaining methyl alcohol and unchanged boric acid. and condensed in the condenser 12. and subsequently conveyed into the still 14.

If desired, the removal of the volatile materials from the drum 3 may lee assisted by innit the injection of a urrent of air or steam hy means of the pipe There-upon, 8 parts of water are introduced to the still 1 through the pipe 13. in. order to hydrolyze the methyl hol-ate and liherato u'iethyl alcohol and horic acid. after which the methyl alcohol. together with any undecomposed methyl horate. is distilled otl' through the pipe 15 into the condenser 16 hy the appli ation of heat to the still 14-, so that the distillate may he recovered from. the pipe H. The aqueous solution, of the horic acid in the still H may he drawn ott hy the pipe 13 and allowed to cool. so as to deposit the horic acid crystals. The amountot water added to the still 1% is usually in the proportion of 23 gallons of water to 100 gallons of the distillate contained therein. although the amount of water may he varied somewhat according to the concentration of the horon compounds in said distillate.

While we have (ltStt'llKll our invention ahovc in detail. we wish it to he understood that, many changes may he made therein without departing from the spirit of our invention.

Ye claim l. The process: which comprises removing the horate from a mixture containing the same hy liherating the hori acid from the horate. adding a lower nmnohydric alcohol thereto. and volatilizing the compound formed hy the alcohol and the horic acid.

2. The process which comprises removing the horate from a mixture of sodium and potassium salts containing the same hy liheralii'ig the horic acid from the horate. add ing a lower monohydrh: alcohol thereto. and 'volatilizing the compound formed hy the alcohol and the horic acid.

'3. The process which comprises removing th horate from a mixture containing the same hy liherating the horic acid from the horatc. adding methyl alcohol thereto. and volatilizing the compound 'lormed hy the alcohol and the horic acid.

4. The process which comprises removing the horate lrom a mixture of sodium and potassium salts containing the same hy ihcrating the horic acid from the horatc. adding methyl alcohol thereto. and volatilizing the compound termed hy the alcohol and the horic acid.

l he process which comprises removing the horate troln a mixture containing the same hy liherating the horic acid from the horate. adding a lower monohydric alcohol thereto. volatilizing the compound 'lormed hy the alcohol and the horic acid. condensing the vapors thus produced. and hydrol ming the distillate.

P. The process which comprises removing the horatc from a mixture o't sodium and potassium suits C(Hlitllldlllgl' the same hy lih crating the horic acid from the hol-ate. adding a lower monohydric alcohol thereto. volatilizing the compound termed by the alcohol and the horic acid. condensing the vapors thus: produced. and hydrolyzing the distillate.

T. The process which comprises removingthe horate trom a mixture containing the same by liberating the horic acid from the horato. adding methyl alcohol thereto, volatilizing the compound formed by the alcohol and the horic acid. condensing the Vapms thus produced. and hydrolyzing the distil late,

The process which comprises removing the horate from a mixture of sodium and potassium salts containing the same by hi)- erating the, horic acid from the hol-ate, adding methyl alcohol thereto. volatilizing the compound formed hy the alcohol and the horic acid. condensing the vapors thus pro duced, and hydrolyzing the distillate.

The process which comprises removing the horate tron: a mixture containing the same hy lilwrating the horic acid from the horate. adding a lower monohydric alcohol thereto. volatiliZing the compound formed by the alcohol and the horic acid. condcns ing the apors thus produced. hydrolyzing the distillate. and distilling oil the alcohol.

10. The process which comprises removing the horate from a mixture of sodium and potassium salts containing the same hy lihcrating the horic acid from the horate. adding a lower uumohydric alcohol thereto. volatilizing the compound formed by the alcohol and the horic acid. condensing the vapors tlillsj produced. lrvdrolyzing the distillate, and distilling oil the alcohol.

1]. The process which LOlTlPllSOS ren'ioving the horate from a mixture containing the same hy lihcrating thc horic acid from the horate. adding methyl alcohol thereto. volatilizing he compound tormed hy the alcohol and the horic acid. condensing the vapors thus produced. hydrolyzing the distillate. and distilling oil the alcohol.

12. The process which comprises removing the horate 'irom a mixture of sodium and potassium salts containing the same 1)) iii)- erating the horic acid from the horate. adding methyl alcohol thereto. volatilizing the compound 'lormcd hy the alcohol and the horic acid. condensing the apors thus produced. lrvdrolyxing the distillate. and distillin; otl" the alcohol.

1 The process which comprises removing the horate. from a mixture contaii'iing the same hy liherating the horic acid From the horate. adding a lower monohydric alcohol thereto. volatilizing the compound formed by the alcohol and the horic acid. condensing the vapors thus produced. hydrolyzing the distillate. distilling otl the alcohol. and clystallizing out the horic acid froin the residue.

14. The process which comprises removing In testimony that \\d ('laiin the foregoing the horutv from a mixture mtuinin; tho, '0 have hereunto set our hands. sumo hy liberating tho lmric acid from the ROBERT P. CALVERT. horatc by moans of the addition of another ()TllO L. THOMAS. 5 acid and adding :1 lower monolrydric nlco- \\"itnesses:

hol thereto. and volntilizing the compound (l. D. Humans, furmvd by the alcohol and boric acid. S. L. Animus.

- Copies of this patent may be obtained for five cents each. by hddre'ssmgthc'Udififiisfdiif o f Pitefifi Washington, D. 0." 

